If you could send something back in time, what would you send and perhaps a reason for doing so.
Dam there are so many things that could be send back where to start!
The technology to develop solar panels faster. Just think how far we could have been if the electric car won out the petrol car!
A delorean 
to prove that it can be done
Imagine their faces when the delorean arrives on the set of back to the future.
so many interesting possibilities, medical encyclopedia set, modern CPU specs with blueprints
Newtonian physics to the Romans. 
I would send a picture of Scarlett Johansen to the Spartans so that they can see that Helen of Troy is not all that special to get into a battle over.
This is the type of forward thinking we need from time travellers.
I would send imagery of the destruction caused by mankind and its greed. I’m sure it won’t change anything though
I would send back some money to invest in Bitcoin and instructions to sell it all off when it hit R300k!
(Whoops! sorry for the thread necro, I didn’t check the date…)